Pressurized fluid systems are often provided with pressure relief capabilities to prevent injury to personnel and damage to equipment. In the event of an overpressure condition, an overpressure valve assembly can be used to establish a bypass or shut-off path for the pressurized fluid.
Valve assemblies can be configured to be normally open (NO) or normally closed (NC). Collapsible members such as buckling pins and rupture disks can be used to control the set point at which such valve members operate to close, or open, respectively.
A particular overpressure relief configuration proposed in the art generally utilizes a downstream main pressure relief valve in series with an upstream overpressure device, such as a rupture disk. The rupture disk generally isolates the downstream valve from normal fluidic flow; that is, the rupture disk is intended to retain the fluid until the overpressure condition is reached, after which the disk ruptures and the pressurized fluid passes to the main pressure relief valve.
A limitation with this approach includes the fact that any fluidic pressure that may develop between the upstream and downstream devices, such as via a leak through or around the rupture disk, will generally tend to alter the differential pressure across the upstream device. In such case, the set point at which the upstream device opens will be undesirably higher than the specified level.
It is thus common to use pressure indicators, such as a human readable pressure gauge, to detect such buildup of pressure between the upstream and downstream devices. When an undesirably high level of intermediate pressure is detected, maintenance actions are required to address the situation, which can include installation of a new, replacement rupture disk in the upstream device.
Another limitation associated with the use of rupture disks in the above configuration is the fact that while rupture disks are generally intended to open in a controlled manner and remain in a single piece, due to the forces involved it has sometimes been found that portions of a ruptured disk can separate and be carried along with the fluidic flow to the main pressure relief valve. This is generally undesirable in that such particles may interfere with the proper opening or subsequent closing of the main valve.
Thus, while the existing art provides a variety of operable solutions, there nevertheless remains a continued need for improvements in the manner in which overpressure conditions in various pressurized fluid system configurations can be detected and relieved. It is to these and other improvements that preferred embodiments of the present invention are generally directed.